Pyongyang state television footage aired Sunday showed North Korean soldiers forming a human bridge during an underwater construction project.

The television segment showed the soldiers engaging in heavy manual labour without safety gear in what was described as a "speed battle" against time, South Korean television network KBS reported.

The video, which aired for about an hour Sunday, showed nearly a dozen North Korean soldiers submerged under water while supporting a wooden plank on their shoulders. Overhead, more soldiers rush across the bridge carrying bricks and mortar – pounding down on the soldiers below.

At one point in the segment, a North Korean female soldier is shown rolling a boulder about 20 inches wide with her bare hands, doing work without a helmet, gloves or any other safety gear. In another scene, North Korean soldiers are seen driving nails into logs as sheets of water pour down on them from cascading waterfalls.

"If the supreme commander instructs the Korean People's Army to hold back the sea they will hold back the sea. If they are ordered to move mountains, they will move mountains," North Korea stated in the video.

The state propaganda footage, timed to coordinate with Kim Jong Un's speeches on launching an era of economic reform, included explanations of the policy initiatives, South Korean news network MBN reported.

During his annual New Year's speech, Kim Jong Un had called for an "all-out fierce battle" in order to realize the party's policies and "initiatives for construction."

But the deployment of inexperienced construction workers or engineers tasked with fast-paced renovation projects has led to accidents, including at a power plant in Mount Paektu, and at least one collapsed apartment building.

Choi Sung-kuk, a North Korean defector who left in 2011, had told South Korea press the problem arises when workers show up just to fill quotas.